The Dometic SlideTopper is designed to protect the top of an RV's slideout room from weather, debris and mildew. It is not intended to be 100% waterproof, due to drips and condensation. To determine which size of SlideTopper you require, measure your room according to the picture below and refer to the chart. The SlideTopper will not work on rooms with a full extension greater than 44". Need to order hardware separately.

 PROP 65 WARNING: This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling. For more information, visit www.P65Warnings.ca.gov